This paper describes a solvothermal approach to synthesize CuInS2 quantum dots (QDs) and demonstrates their application as a potential electron accepting material for polymer-based hybrid solar cells, for the first time. The CuInS2 QDs with a size of 2-4 nm are synthesized by the solvothermal method with 4-bromothiophenol (HSPh) as both reduction and capping agents, and characterized by XRD, XPS, TEM, FT-IR, cyclic voltammetry (CV), and absorption and photoluminescence spectra. Results reveal that the CuInS2 QDs result from the solvothermal decomposition of a soluble organic sodium salt as an intermediate precursor formed by simple reactions among CuCl2, InCl3, HSPh and Na2S at room temperature; they have an ionization potential (IP) of -5.8 eV and an electron affinity (EA) of -4.0 eV and can quench effectively the luminescence of poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV). Due to the favorable IP and EA positions with respect to MEH-PPV, the CuInS2 QDs act as an effective electron acceptor for the hybrid solar cells based on MEH-PPV/CuInS2-QDs blends with a wide spectral response extending from 300 to 900 nm, by allowing the efficient charge separation for neutral excited states produced either on the polymer or on the QDs. The MEH-PPV/CuInS2-QDs solar cells exhibit a promising open circuit voltage (V-oc) of 0.62 V under the monochromic illumination of 15.85 mW cm(-2) at 470 nm. The charge transfer processes in the solar cells are also described
For characterization of polymer-based solar cells with vertically aligned ZnO nanorod arrays (ZnO-NAs) by intensity modulated photocurrent spectroscopy (IMPS), a dynamic IMPS model is developed, where the structure-related charge generation and transport dynamics are considered. The model describes the IMPS responses affected by the phase shift φ n (ω) due to the exciton diffusion property (ω 0 ) and the structurerelated device ideality factor N, the electron diffusion coefficient D e , the exciton dissociation rate S, and the device structure (e.g., nanorod length d and interspacing l). The main expectations of the model are confirmed by the experimental data of the polymer/ZnO-NA cells with d ) 180-650 nm, offering mechanistic information on the structure-related charge generation, charge transport, and device performance. The presence of the φ n (ω) makes IMPS response not spiral into the origin and the phase angle in its Bode plot not tend to 90°; the d-dependent direct diffusion (DD) and diffusion-reflection (DF) transport processes are normally involved in the travel of injected electrons to the collection electrode; the incident photon-to-current conversion efficiency (IPCE) and the transit time (τ D ) for DD transport under the influence of DF process reach their peak values at d ≈ 500 nm, and the φ n (ω) effect on electron transport is affected by ω 0 , D e , and S. Satisfactory fittings of measured IMPS responses to the model further reveal that the d dependence of the IPCE or the photocurrent actually originates from the S value governed by d-dependent exciton generation and dissociation; when changing d, a larger number of electrons for DD transport causes a smaller N or a more remarkable φ n (ω) effect; a longer τ D is accompanied by a larger RC effect of the ZnO electrode. Those results clearly suggest that a highly efficient polymer/ZnO-NA device requires d ≈ 500 nm and l ) 5-10 nm, along with a high interfacial exciton dissociation efficiency.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.